Is the M2 the same as the M1A1 carbine I remember from my JROTC days in the late 50’s? IIRC, it had a selector and a banana mag.
The M1A1 should NOT have had the selector. It is designated as semi-auto only. It should have had a folding stock, it was designed mainly for paratroops. It is entirely possible some local armorer disregarded protocol and converted some to select fire, however officially the M1 and M1A1 carbines were semi-auto, the M2 and M3 carbines were select fire.